Improving the Efficiency and Safety of Human CCR5 Gene Editing by Selection of Optimal Guide RNAs for SpCAS9 and CAS12A

Advances in CRISPR/Cas-mediated genome editing have opened up treatment alternatives for many human diseases, including HIV infection. Knockout of the CCR5 gene as a potential way to treat HIV infection has long been studied. Here we analyzed guide RNAs for SpCas9 and AsCas12a nucleases targeting CCR5 gene which had been previously studied and selected the most effective among them. We also designed novel guide RNAs for the same nucleases using bioinformatics resources. We compared the efficiency of target site cleavage for all selected gRNAs using three nucleases: wt SpCas9, SpCas9-HF1-plus, and AsCas12a, as well as their off- target activities. We demonstrated that among the tested guide RNAs two for SpCas9-HF1-plus and three for AsCas12a exhibited high cleavage activity, cutting CCR5 gene in 60–72% of cells, and had off-target activities below the limit of detection. Thus, these guide RNAs may be candidates for future development of gene therapies against HIV infection.